a study of bb-1701 in previously treated participants with human epidermal growth factor receptor 2 (her2)-positive or her2-low unresectable or metastatic breast cancer

Conditions: Breast Cancer

Summary: the primary purpose of the dose optimization (part 1) of this study is to assess the safety and tolerability of bb-1701 and to determine the recommended dose (rd) of bb-1701 for dose expansion (part 2). the primary purpose of dose expansion (part 2) is to assess the antitumor activity of bb-1701 at rd in the selected population(s) of breast cancer (bc).


Eligibility criteria:
inclusion criteria * male or female, aged \>=18 years at the time of informed consent. * metastatic or unresectable bc that is histologically confirmed to be either her2-positive (defined as an immunohistochemistry \[ihc\] status of 3+, or a positive in situ hybridization \[ish\] test \[fluorescence, chromogenic, or silver-enhanced ish\] if ihc status is 2+) or her2-low (defined as an ihc status of 1+, or 2+ and negative ish) per the american society of clinical oncology/college of american pathology guidelines as documented prior to trastuzumab deruxtecan (t-dxd) treatment. * must have previously received t-dxd. * sufficient tumor tissue is required for her2 status testing at a central laboratory. * measurable disease per recist 1.1 as assessed by the investigator. participants with bone only disease may be eligible if there is a measurable soft tissue component associated with the bone lesion. * must have previously received at least 1 but no more than 3 prior chemotherapy-based regimes in the unresectable or metastatic setting. if recurrence occurred during or within 6 months of (neo) adjuvant chemotherapy, this would count as 1 line of chemotherapy. * if hr-positive her2-low bc, must have previously received endocrine therapy and is not expected to further benefit from it. * ecog ps 0 or 1. * life expectancy of at least 3 months. * adequate organ function and laboratory parameters. exclusion criteria * presence of brain or subdural metastases, unless participant has completed local therapy and has discontinued the use of corticosteroids for this indication for at least 2 weeks prior to starting treatment in this study. * diagnosed with meningeal carcinomatosis. * received anticancer therapy (chemotherapy or other systemic anticancer therapies, immunotherapy, radiation therapy, etc) or an investigational drug or device within the past 28 days or 5 half-lives, whichever is shorter. * prior treatment with eribulin. * any prior allergic reactions of grade \>=3 to monoclonal antibodies or contraindication to the receipt of corticosteroids or any of the excipients (investigators should refer to the prescribing information for the selected corticosteroid). * residual toxic effects of prior therapies or surgical procedures that is grade \>=2 (except alopecia or anemia). * grade \>=2 peripheral neuropathy or history of grade \>=3 peripheral neuropathy or discontinued any prior treatment due to peripheral neuropathy. * active pneumonitis/interstitial lung disease (ild) or any clinically significant lung disease (example, chronic obstructive pulmonary disease), history of grade \>=2 pneumonitis/ild, or received radiotherapy to lung fields within 12 months of cycle 1 day 1 of study treatment. * congestive heart failure greater than (\>) new york heart association class ii or left ventricular ejection fraction (lvef) less than (\<) 50 percent (%) measured by multigated acquisition scan (muga) or echocardiogram. * has a corrected qt interval prolongation per fridericia formula (qtcf) \>470 millisecond (ms) (for both males and females) based on screening triplicate 12-lead ecg. * concomitant active infection requiring systemic treatment, except: * if known to be human immunodeficiency virus (hiv)-positive, must be on anti-hiv therapy for at least 4 weeks and have a clusters of differentiation 4+ t-cell (cd4+) count \>=350 cells per microliter (cells/mcl) and an hiv viral load \<400 copies per milliliter (copies/ml). * if meets the criteria for anti-hepatitis b virus (hbv) therapy, must agree to take anti-hbv therapy, if known to be hbv-positive as defined by positive hepatitis b surface antigen or hepatitis b core antibody. hbv viral load must be undetectable. * if known to be hepatitis c virus (hcv)-positive must have completed curative therapy for hcv. hcv viral load must be undetectable. * known history of active bacillus tuberculosis (tb). * any medical or other condition which, in the opinion of the investigator would preclude the participant's participation in the clinical study.

Keywords: breast cancer breast carcinoma unresectable or metastatic breast cancer her2-positive or her2-low unresectable or metastatic breast cancer bb-1701